The present invention relates to a socket for installing a daughter board on which electronic parts are mounted, such as a memory module.
In the field of personal computers and the like, when a daughter board on which electronic parts are mounted, such as a memory module, is connected to a mother board, the connection is usually made through a socket which is fixedly mounted on the mother board by soldering or the like. As such a type of socket, in order to make the installation of the daughter board easy, a zero insertion force (ZIF) type socket has been often used.
In the use of the ZIF type socket, a daughter board is inserted in a slantwise direction relative to the socket, and after the insertion, the daughter board is moved to the position parallel to the socket, thereby engaging both ends of the daughter board with latches disposed at both sides of the socket to fix the position.
FIGS. 9 and 10 show an example of a conventional socket. This socket 1 has the substantially same structure as the one disclosed in Japanese Unexamined Patent Publication No. 8-55651 (55651/1996), wherein contacts 2a exposed from the lower face of a housing 2 are attached to a mother board, not shown in the drawing, by soldering. Further, arms 3 are oppositely disposed at both ends of the housing 2, and latches 4 are attached and fixedly mounted on the opposed faces of the arms 3.
When a terminal portion 5a formed on an edge 5c of a daughter board 5 is inserted in a slantwise direction relative to a socket 2b of the housing 2, notches 5b formed at both ends of the daughter board 5 are kept at the position at which they will be in alignment with hook members 4a formed on the latches 4.
When the daughter board 5 is pressed downward in the drawing around the edge 5c on which the terminal portions 5a are formed, the hook members 4a abut on the notches 5b and are thereby pressed outwardly and the daughter board 5 enters beneath the hook members 4a, and as shown in FIG. 10, the upper and lower faces of the daughter board 5 are sandwiched between the hook members 4a and tongue members 3a curvedly formed on the arms 3, and the lower faces of the hook members 4a of the latches 4 are engaged with the upper edge portions of the notches 5b, thereby securing the position of the daughter board.
At the position shifted from the center of the edge 5c of the daughter board 5 toward either one side edge, a notch 5d is formed. In a slot 2b of the socket 1, a projection 2c for positioning is provided corresponding to the notch 5d. 
As a result, when the edge 5c of the daughter board 5 is inserted into the slot 2b of the socket 1, if the upper and lower faces of the daughter board are upside down, the projection 2c for positioning abuts on the edge 5c so that unwanted insertion can not be made. Further, if the daughter board is inserted appropriately, the notch 5d of the edge 5c fits in the projection 2c for positioning, whereby the contacts 2a of the socket 2 are in alignment with the terminal portions 5d of the daughter board 5.
However, in the conventional socket 1, due to the dimensional error unavoidable in the production, looseness is caused to some extent between the projection 2c for positioning formed on the slot 2b and the notch 5d formed on the edge 5c of the daughter board 5. Accordingly, when the alignment of the terminal is made to have an extremely narrow pitch width, there is a possibility that the position of the contacts 2a of the socket 1 may be out of alignment with the position of the terminal portions 5d of the daughter board 5.
Accordingly, it is an object of the present invention to provide a socket wherein even if the alignment of the terminal portions of the daughter board is made to have a further narrow pitch width, the position of the contacts 2a of the socket 1 is kept to be in alignment with the position of the terminal portions of the daughter board.
In order to accomplish the above objects, the first aspect of the present invention provides a socket for installing a daughter board having electrical parts mounted thereon and terminal portions aligned with a predetermined pitch on one edge, which comprises:
a housing comprising a slot for receiving the edge of the daughter board on which the terminal portions are aligned, and contacts which are provided on an inner side of the slot and are to be contacted to the terminal portions with pressure, and
a pair of latches which extend from both sides of the housing toward an opening direction of the slot and engage with both sides of the daughter board when the edge of the daughter board is inserted into the slot and moved down against the urging force of the contacts,
wherein in the edge of the daughter board, a notch is formed at a position shifted from the center of the edge toward either side edge,
in the slot of the housing, a projection for positioning is formed at a position corresponding to the notch which is to be inserted into the notch, and
on at least one side of the projection for positioning, an elastic member which is to be pressed against an inner side wall of the notch in the edge of the daughter board is provided.
According to the first aspect of the present invention, when an edge of a daughter board on which a terminal portions are disposed is inserted into a slot of a socket, a projection for positioning disposed in the slot is fitted in a notch formed at the edge of the daughter board, and since an elastic member is disposed on at least one side of the projection for positioning, the projection for positioning can be inserted into the notch in such a state that the elastic member abuts on at least one inner side wall of the notch of the daughter board with pressure.
As a result, when elastic members are disposed at both sides of the projection for positioning, the daughter board is relatively moved to such a position that both elastic members are well balanced during the step of inserting the daughter board into the slot of the socket, thereby keeping the alignment of the terminals of the daughter board and the contacts of the socket. Further, when the elastic member is disposed at one side of the projection for positioning, during the step for inserting the daughter board into the slot of the socket, the side face of the projection for positioning on which no elastic member is disposed is pressed against the corresponding inner side face of the notch of the daughter board, thereby keeping the alignment of the terminals of the daughter board and the contacts of the socket.
In order to accomplish the above objects, the second aspect of the present invention provides a socket for installing a daughter board having electrical parts mounted thereon and terminal portions aligned with a predetermined pitch on one edge, which comprises:
a housing comprising a slot for receiving the edge of the daughter board on which the terminal portions are aligned, and contacts which are provided on an inner side of the slot and are to be contacted to the terminal portions with pressure, and
a pair of latches which extend from both sides of the housing toward an opening direction of the slot and engage with both sides of the daughter board when the edge of the daughter board is inserted into the slot and moved down against the urging force of the contacts,
wherein in the edge of the daughter board, a notch is formed at a position shifted from the center of the edge toward either side edge,
in the slot of the housing, a projection for positioning is formed at a position corresponding to the notch which is to be inserted into the notch, and
an elastic member is provided at either side edge of the housing, the elastic member being used to press the either side edge of the daughter board to contact the notch against the projection for positioning with pressure.
According to the second aspect of the present invention, when an edge of a daughter board on which terminals are disposed is inserted into a slot of a socket, a projection for positioning formed in the slot is fitted in a notch formed at an edge of the daughter board, and in such instance, an elastic member disposed at either edge portion of a housing is pressed against a side edge of the daughter board and the notch is thereby pressed against the projection for positioning, thereby keeping the alignment of the terminals of the daughter board and the contacts of the socket.